Heavy oils and natural bitumens contain a number of high molecular weight compounds and aggregates that cause challenges for upgrading such oil. These challenges impact producing and refining heavy oil. Components of heavy oil and bitumen include paraffin, naphthene, olefin, wax, resin, asphaltene, and the like. The chemical structures of these components include unsaturated hydrocarbon or aromatic portions. Heavy oil also contains heavy metals (e.g., vanadium, nickel, molybdenum, etc.) as well as heteroatoms (e.g., nitrogen, sulfur, and oxygen). The heteroatoms may substitute for carbon atoms in the various heavy oil components. Some of these components are toxic and negatively affect the environment due to, for example, aromatic content.
Heavy oil has been characterized as having an API gravity from 10° to 20°. Extra-heavy oil and natural bitumen display an API gravity lower than 10°. The difference between extra-heavy oil and bitumen is based on a viscosity at reservoir conditions: the viscosity of extra-heavy oil is lower than 10,000 centipoise (cP), while the viscosity of bitumen is higher than 10,000 centipoise (cP). The viscosity of heavy oil and bitumen, further referred to as heavy oil, is one reason why their production has proven difficult, expensive, and time consuming. Furthermore, heavy oil may deposit in the pores of formations, blocking the flow of fluids. Additionally, components of heavy oil, e.g., asphaltenes, can precipitate from a stream of oil and coat boreholes, production tubing, and transport lines. Before use, heavy oil is upgraded, which is challenging for many reasons including high temperature and catalyst requirements as well as interference by organometallic compounds associated with heteroatoms in the heavy oil components. Moreover, heavy oil components can foul processing equipment and poison catalysts. Thus, materials and methods for upgrading heavy oil would be well received in the art.